PISTON KIT YAM XS650 76.50, WOSSNER K8818D150-2 680cc

This piston kit is designed for Yamaha XS650 motorcycles manufactured between 1974 and 1981. It includes a set of four forged Wossner pistons with a +1.50mm oversize (76.50mm bore), engineered for enhanced durability and performance. The elliptical piston design ensures even distribution of thrust loads under heat expansion, helping to prevent localised stress and piston collapse. Manufactured in Germany, this kit supports both standard and slightly increased engine displacements.

Features

• Set of 4 forged Wossner pistons

• +1.50mm oversized bore (76.50mm, actual piston diameter 76.44mm)

• Elliptical design for balanced heat expansion and load distribution

• Designed for optimal heat transfer to cylinder walls

• Made in Germany

Specifications

• Part Number: K8818D150-2

• Bore Size: 76.50mm (actual piston size 76.44mm)

• Oversize: +1.50mm

• Displacement: 679 / 688cm³

• Stroke: 74.00mm

• Clearance: 0.06mm

• Wossner Compression Ratio: OEM

• OEM Compression Ratio: 8.40:1

• Dome Volume: +23.40cm³

• Compression Height: 29.00mm

Cross-Reference OEM Part Numbers

• Clips: CW20

• Piston Pin: WP068

• Rings: 765XDS

Vehicle Fitments

• Yamaha XS650 1974–1981